The Network Time Protocol (NTP) is used to synchronize the time of a
computer client or server to another server or reference time source,
such as a radio or satellite receiver or modem.  It provides accuracies
typically within a millisecond on LANs and up to a few tens of
milliseconds on WANs relative to Coordinated Universal Time (UTC) via a
Global Positioning Service (GPS) receiver, for example.  Typical NTP
configurations utilize multiple redundant servers and diverse network
paths in order to achieve high accuracy and reliability.  Some
configurations include cryptographic authentication to prevent
accidental or malicious protocol attacks and some provide automatic
server discovery using IP multicast.
